Black boxes are designed to specifications. The specification defines the inputs and outputs. It also defines the tools to replace the unit (usually nothing more than a #2 Phillips-head screwdriver), and the bulk and weight (they always need to be carried by one man, and fit through a door, if possible).
So philosphers are coming up with abstract theories about the mind as an object that can be removed using a screwdriver and is small enough to be carried by one man. No wonder philosophy doesn't pay much - I could have told you that! Though I'd use a scalpel and a drill myself. Verloren